<?php

namespace app\admin\model;

use think\Model;
use think\Db;

class ShortTextCompare extends Model
{
	#计算匹配文字$arr1[$i]的最小匹配偏移值
	public static function PosOffset($arr1, $i, $arr2){
		$len2 = count($arr2);
		$arr2_reverse = array_reverse($arr2);
		for($j = 0; $j < $len2; $j++){
			$rev_num = abs($i-$j)-1;
			$rev_data = isset($arr2_reverse[$rev_num]) ? $arr2_reverse[$rev_num] : '';
			$notrev_data = isset($arr2[$i-$j]) ? $arr2[$i-$j] : '';
			if($i+$j >= 0 && $arr1[$i] == ($i-$j >=0 ? $notrev_data : $rev_data)){
				return $j;
			}
			if($i+$j < $len2 && $arr1[$i] == $arr2[$i+$j]){
				return $j;
			}
		}
		return $len2;
	}
	
	#计算匹配文字$arr1[$i]对于整体相似度的贡献量
	public static function CC($arr1, $i, $arr2){
		$len2 = count($arr2);
		$len2_float = sprintf("%.2f", $len2);
		$temp = self::PosOffset($arr1, $i, $arr2);
		$data = ($len2 - $temp) / $len2_float;
		return $data;
	}
	
	#计算短语$arr1相对于短语$arr2的相似度sc
	public static function SC($arr1, $arr2){
		$sc = 0.0;
		$len1 = count($arr1);
		for($i = 0; $i < $len1; $i++){
			$sc += self::CC($arr1, $i, $arr2);
		}
		$sc /= $len1;
		return $sc;
	}
	
	#计算短语$arr1与短语$arr2之间的相似度
	public static function S($arr1, $arr2){
		$temp1 = self::SC($arr1, $arr2);
		$temp2 = self::SC($arr2, $arr1);
		return ($temp1 + $temp2)/2;
	}
	
	#将字符串转换成数组存储
	public static function CharToArr($str){
		 return preg_split('/(?<!^)(?!$)/u', $str );
	}
}